Inert gas absorption refrigeration system, including a fan



March 1, 1949. MOODY 2,463,409

INERT GAS ABSORPTION REFRIGERATION SYSTEM, INCLUDING A FAN Filed July 9,1942 2 Sheets-Sheet 1 Fig.1

INV ENTOR .DwiglztLjVoody ATTORNEY March 1, 1949. D. L. MOODY 2,463,409

INERT GAS ABSORPTION REFRIGERATION SYSTEM, INCLUDING A FAN Filed July 9,I942 2 Sheets-Sheet 2 INVENTOR Dwight L. Moody May 152 ATTORNEY PatentedMar. 1, 1949 INERT GAS ABSORPTION REFRIGERATION SYSTEM, INCLUDING A FANDwight L. Moody, Akron, Ohio, assignor to The Hoover Company, NorthCanton, 01110, a corporation of Ohio Application July 9, 1942, SerialNo. 450,274

4 Claims. 1

This invention relates to refrigeration and more particularly to meansfor circulating the mediums in an air-cooled three-fluid absorptionrefrigerating machine using ammonia as the refrigerant, water as theabsorbent and an inert pressure equalizing medium such as nitrogen orhydrogen.

In such machines a closed circuit is provided between the evaporator andthe absorber for the circulation of the inert gas therebetween. Theinert gas is for the purpose of equalizing the pressures throughout theentire machine, all of the parts of which are in open communication, andfor carrying refrigerant vapor from the evaporator to the absorber.

In the evaporator, the refrigerant liquid is vaporized by diffusion intothe inert gas and in the absorber the refrigerant vapor is absorbed outof the inert gas. A closed circuit is also provided between thegenerator and absorber for the circulation of the absorption solution,usually'consisting of a water solution of ammonia. In the generator,refrigerant vapor is driven from the solution by the application of heatand in the absorber the weak solution takes up refrigerant vapor fromthe inert gas. Some means must therefore be provided for circulating theinert gas between the evaporator and the absorber and the solutionbetween the generator and the absorber.

In prior art machines it has been the usual practice to circulatetheinert gas thermosiphonically or by differences in specific weights ofdifferent columns of the inert gas and to circulate the solution by heatoperated vapor liquid lift pumps. Such machines operate satisfactorilyunder ordinary circumstances but in hot climates and in high roomtemperatures they are unsatisfactory because they operate .ineflicientlyand have very low capacity. The problem could be solved if some means isprovided for circulating the mediums within the apparatus which is notaffected by changes in ambient temperature.

It has been proposed to use mechanical pumps for the purpose ofcirculating themediums insuch refrigerating systems, but the applicationof mechanical pumps to these systems is not a simple matter. Theinternal pressures of air cooled systems of this type vary from 250 to400 pounds per square inch under normal operating conditions and undercertain abnormal conditions they go to a much higher value. Before beingput into use, such systems are hydraulically tested up to 800 pounds persquare inch.

Thus it is practically impossible to use me- 2 chanical pumps havingmoving parts extending through the walls of the system.

In order to solve this problem a way must be found to hermetically sealthe moving parts of the mechanical circulator unit on the interior ofthe apparatus and the present invention has to do with the solution ofthat problem.

In some localities a supply of electricity is not available and it isdesirable to provide a refrigerating machine which can be operated byheat alone and still have some means for positively circulating themediums within the apparatus which is not affected by changes in ambienttemperature.

According to one aspect of the present invention a two part boiler isprovided, one part for driving the refrigerant vapor from the solutionand the other for generating steam which is used for driving the inertgas fan. A steam turbine is connected to the driver of a magnetictransmission and power 50 derived is transmitted directly through thewalls of the apparatus to a magnetic follower connected to the inert gasfan and both the follower and the fan are hermetically sealed within thewalls of the system.

In communities where electricity is available it is desirable to drivethe gas fan by an electric motor so that the circulation of the mediumswithin the apparatus will be independent of ambient temperature and thecapacity and emciency of the machine will not be adversely affected bychanges in ambient temperature.

According to another aspect of this invention the gas fan is driven by asmall electric motor positioned entirely upon the exterior of theapparatus so as to be unaffected by the high pressures and corrosiveatmosphere on the interior of the apparatus and the power developed bythis motor is transmitted through the walls of the apparatus by means ofa magnetic transmission. The

motor is directly connected to the magneticdriver and the magneto-motiveforce of the driver is transmitted through the walls of the apparatus toa magnetic follower which is directly connected to the fan and both arehermetically sealed Within the walls of the system.

In both cases the magnetic follower and fan can be made of a materialwhich is not affected by the corrosive atmosphere on the interior of theapparatus. For example, the follower can be made of magnetic stainlesssteel which is very resistant to corrosion by ammonia. If the rotor ofthe motor itself were to be positioned in the interior of the apparatussome means would have to be provided for protecting its windings fromthe corr sive atmosphere. In addition, the present inve tion makes itpossible to reduce materially the load on the internal bearings wherebythe bearing problem is simplified.

According to this invention the internal bearings are lubricated byliquid normally contained in the apparatus which simplifies thelubrication problem. A sodium chromate corrosion inhibitor is usuallyprovided in refrigerating systems of the type to which this inventionrelates to protect the metal parts of the boiler and solution circuitfrom attack by ammonia. Ordinary lubricating oil will react with thischromate inhibitor to produce a soapy sludge which will interfere withthe proper circulation of the mediums. Thus by positioning the entirepower unit on the exterior of the apparatus and lubricating the internalbearings by a liquid medium normally contained in the apparatus, thelubrication problem is very much simplified.

According to this invention. the driver is a permanent magnet which maybe made of a magnetic alloy having the proper proportions of nickel,aluminum, chromium and iron, purchasable on the open market under thetrade name of Alnico or some other suitable permanent magnet material.The driver magnet is separated from the follower by a thin shell ofnonmagnetic stainless steel. The follower may be made of magneticstainless steel or it may be a permanent magnet-but in any event itshould be very resistant to the corrosive atmosphere on the interior ofthe apparatus.

Other objects and advantages of this invention will become apparent whentaken in connection with the accompanying drawings, in which:

Figure 1, is a. diagrammatic representation of a refrigerating apparatusaccording to this invention;

Figure 2 is a detail view partly in section, showing the details of thedriver and follower. arrangement for driving the circulating fan; and

Figure 3 is a modification showing an electric motor for driving thedriver magnet.

Referring to Figure 1 of the drawings, there is disclosed a three-fluidabsorption refrigerating system comprising a boiler B, an analyzer D, anair-cooled rectifier R, a tubular air-cooled .vertically positionedcondenser C, an evaporator E, a gas heat exchanger G, a tubularair-cooled absorber A, a solution reservoir S, a liquid heat exchangerL, and a circulation fan F which is driven by a turbine T. The way inwhich the turbine is driven will be described in more detailhereinafter.

The above-described elements are interconnected by various conduitsto'form a plurality of gas and liquid circuits constituting a completerefrigerating system to which reference will be made in more detailhereinafter.

The refrigerating system will be charged with a suitable refrigerantsuch as ammonia, a suitable absorbent such as water, having a suitablecorrosion inhibitor such as sodium chromate dissolved therein and asuitable inert pressure equalizing medium such as nitrogen or hydrogen.

The boiler B will be heater in any suitable manner as by an electriccartridge heater or by a gas burner as may be desired and the burner orheater may be controlled by a thermostatic control responsive toevaporator temperature in any manner well known in the art.

The application of heat to the boiler B liberates refrigerant vapor fromthe strong solution contained therein. The vapor so liberated passesupwardly through the analyzer D in counterfiow relationship to strongsolution flowing downwardly through the analyzer. Further refrigerantvapor is generatedin the analyzer by the heat of condensation ofabsorption solution vapor generated in the boiler. The refrigerant vaporis conducted from the upper portion of the analyzer D to the upperportion of the condenser C, through a conduit [3 which includes theaircooled rectifier R and a liquid collecting or gas separation chambervessel l4. Any vapor of absorption solution passing through the analyzeris condensed in the rectifier R and fiows backwardly through the conduitl 3 into the collecting chamber I4. The purpose of collecting the liquidin chamber M will be described in more detail hereinafter. Therefrigerant vapor is liquefied in the condenser by heat exchangerelationship with atmospheric air and is discharged from the bottomportion thereof through a conduit l5 into a downwardly extending conduitI6. The bottom portion of conduit l6 connects to the bottom portion ofan upwardly extending conduit ll through a U-bend l8. The conduit 55 isappreciably longer than the conduit l! for a purpose to be described inmore detail hereinafter. Conduit I1 opens at its upper end into aconduit 20 which discharges into the evaporator in a manner to bedescribed more fully herein- 'above the solution level normallyprevailing in the boiler-analyzer-reservoir system whereby some meansmust be provided to elevate the absorption solution to the top of theabsorber A. For this purpose a small bleed conduit 21 is con-- nected tothe discharge conduit 28 of the circulating fan F and leads to thejunction of the conduits 24 and 25, which junction is below the solutionlevel normally prevailing in the reservoir whereby the weak solution iselevated into the top of the absorber by gas lift action.

In the absorber the weak solution flows downwardly by gravity incounterfiow to the rich pressure equalizing medium refrigerant vapormixture flowing upwardly therethrough. The refrigerant vapor content ofthe mixture is absorbed in the absorption solution and the heat ofabsorption is rejected to the surrounding air 'by the air-cooling finswhich are mounted on the exterior walls of the absorber vessel. Strongsolution formed in the absorber discharges into a conduit 32 which opensinto-the inner pass of liquid heat exchanger L. From the inner pass ofliquid heat exchanger L, the strong solution is conveyed to the upperportion of the analyzer .D by conduit 33 whereby it flows downwardlythrough the analyzer in counterflow to upward- ;he conduit 35 into thesuction side of the cirzulating fan F in which it is placed under preseme and discharged through the conduit 28 into rhc outer pass of gas heatexchanger G, through i, downwardly extending conduit 36 into the bot-;om of the evaporator E. v

The conduit 20 opens into the bottom portion at conduit 38 whereby theliquid refrigerant supplied to the evaporator enters the samesimultaneously with the pressure equalizing medium which is placed underpressure by the circulating fan F. The diameter of the conduits of theevaporator are relatively small whereby the pressure equalizing mediumflows through them at a relatively high velocity. The rapidly flowingpressure equalizing medium sweeps or drags the liquid refrigerant withit through the evaporator into the box-cooling conduit 40 as therefrigerant is evaporating by diffusion into the pressure equalizingmedium to produce refrigeration. In the conduit 48 the velocity of theinert gas stream is relatively slow and by reason of the large diameterof that conduit, the liquid refrigerant flows therethrough by gravity.

The rich pressure equalizing medium refrigerant vapor mixture formed inthe evaporator is conducted therefrom into the inner pass of the gasheat exchanger G through a conduit 45. The opposite end of the gas heatexchanger G communicates with the bottom portion of the absorber Athrough a conduit 48. In the absorber A the rich pressure equalizingmedium refrigerant vapor mixture flows upwardly in counterfiow toabsorption solution whereby the refrigerant vapor content of the mixtureis absorbed by the weak solution.

The bottom coil of the evaporator E is provided with a drain conduit 48which opens into the strong solution return conduit 32. The conduit 48opens into the top portion of the bottom coil of the evaporator wherebyit will not completely drain said conduit. The upper portion of thedischarge conduit l5 of the condenser is vented through a vent conduit49 into the inner pass of the gas heat exchanger G. The solutionreservoir S is vented through a conduit 50 into suction conduit 35 ofthe circulating fan.

The circulating fan F places the pressure equalizing medium dischargedtherefrom under small pressure in the neighborhood of a pressure of 4 /2inches of water. In order to prevent this pressure, which also prevailsin the conduit 36, from being carried back through the condenser dis-,charge conduit, the condenser and conduit l3 to the analyzer, conduit 18has been made appreciably longer than the conduit l 1 whereby a pressurebalancing column ofliquid is formed in the conduit l6 which extendsabove the point of connection between the conduit I! and 20 a distancesufficient to overcome pressure produced by the circulating fan F in theconduit 36.

A conduit 5| including a liquid trap 52 leads condensate from the vessell4 to the top of the casing 53 of the fan F. A conduit 54 leads thecondensed solution vapor from the top portion of the casing 53 to thelower part thereof. The condensed solution vapor is led from the lowerpart of the casing 53 to the solution circuit by conduit 55. In flowingthrough the casing 53, the condensed vapor lubricates the moving partsof the fan F in a manner to be more fully described hereinafter.

A partition 56 divides the boiler B into two chambers 51 and 58. Chamber5! contains the absorption solution for the refrigerating system opening12.

while the chamber 58 contains water so that when heat is applied to theboiler B, steam is generated in the chamber 58. The steam generated inthe chamber 58 is led by conduit 59 to the reaction steam turbine T andpasses therethrough to drive the same. From the turbine T the steam isled to the steam condenser 50 where it is condensed and flows by aconduit to the water reservoir 6|. The water reservoir 8| is connectedby conduit 62 to the chamber 58. The steam generating system is chargedwith sufflcient water that the chamber 58 is always filled with water.

It is to be noted that when the boiler B is energized sometime elapsesbefore refrigerant vapor is being condensed in the condenser C and thata similar interval elapses before sufficient steam is led to the turbineT to drive the same. Thus neither the inert gas, the solution or therefrigerant will be circulated until refrigerant vapor is beingcondensed in the condenser C and all of the mediums in the apparatuswill be circulated by the time that liquid refrigerant is beingdelivered to the evaporator E.

Referring to Figure 2, the turbine T is suitably mounted for rotation ina housing 53 rigidly connected to the fan housing 53 and is rigidlyconnected to a driving'magnet 64 having either two or four poles. Thedriving magnet 54 is preferably a permanent magnet formed of anymaterial from which permanent magnets can be made but is preferably madefrom an alloy having suitable proportions of nickel, aluminum, chromiumand iron, purchasable on the open market under the trade-name Alnico."

The fan F is supported for rotation in the housing 53 by bearingassemblies 55 and 55 and shaft 51. Rigidly connected to the upper end ofthe shaft 61 is a magnetic follower 58 having poles corresponding innumber to the poles on the driving magnet 64. The magnetic follower 68may be a permanent magnet or may be made of any magnetic material but ispreferably made of a stainless magnetic steel which is very resistant tocorrosion. The driving magnet 54 and the magnetic follower 68 areseparated from each other by a thin shell 69 of non-magnetic stainlesssteel which hermetically seals the interior of the fan casing 53 fromthe housing 63. It has been found that the shell 59 may be made 0.20inch in thickness and still withstand the high pressures within theinterior of the system.

Secured to the lower end of the magnetic followef 58 and rotatabletherewith is a conical member 10 having an inwardly extending portion Hwhich forms with the follower 68 an annular An annular baffle 13 issecured to the inner periphery of the casing 53 and has a downwardlyturned lip 14 directly above the opening 12. A second annular baifle 15having an upwardly extending annular lip 15 is secured to the innerperiphery of the casing 53 to separate the fan F from the upper part ofthe casing 53.

The condensed absorbent vapor which flows by conduit 5| from the vesselM to the upper end of the casing 53 falls onto the baffle 13 and fromthence flows over the lip 14 through the opening 12 and into the chamber11 formed by the members l0 and I l. During rotation this solution willbe held by centrifugal action in the outer periphery of the chamber 11and eventually some of the solution will overflow from the chamber 11and bethrown outwardly against the inner walls of the casing 53.However, when rotation stops the liquid trapped in the chamber 11 will 71 fiow through an opening 18 and overflow into the cup-shaped member 19which is secured to the bearing assembly 66 where it will be in aposition to lubricate the bearing assembly 68 during the next runningperiod.

The solution which is thrown outwardly against 4 the inner wall of thecasing 53 will be collected on the annular bailie 15 by the upstandinglip 16 which will cause it to flow through the conduit 54 into the lowerpart of the casing 53 so as to lubricate the lower bearing assembly 65.The lip 16 prevents liquid from contacting the fan F from above and thethrow-oil ring 80 prevents liquid from creeping up the shaft 61 frombelow. Excess liquid is led from the lower part of the casing 53 back tothe solution circuit by conduit 55. Division plate 8| having an openingtherein cooperates with the baifle 15 to form a pressure chamber for thefan F and with the division plate 82 to form a suction chamber.

When the boiler B is energized, the steam generated as previouslydescribed, will drive the turbine T and rotate the driving magnet 64.The magnetic lines of force will be transmitted through the non-magneticshell 69 to the magnetic follower 68. If the magnetic follower 68 tivelycirculating all of the mediums in a threefiuid absorption refrigeratingmachine independently of changes in ambient temperature in which all ofthe. parts of the power-producing means are located exteriorly of thewalls of the system so that they cannot be affected by the corrosiveatmosphere within the system. At the same time power is transmittedthrough the walls of the system in a simple manner. The magnetic flux ofthe driven member in the form of a permanent magnet is transmittedthrough a thin portion of the walls of the system made of nonmagneticmaterial to a magnetic follower her-- metically sealed within thesystem, which follower drives the circulating fan. In addition, theinternal moving parts are lubricated by a liquid medium normallycontained within the system so as to eliminate lubrication difliculties.

While I have shown but a number of modifications of my invention, it isto be understood that these modification are to be taken as illustrativeonly and notin'a limiting sense. I do not wish to be limited to theparticular structure shown is a permanent magnet, its north poles willtend .1

to follow the south poles of the driver 64 with the result that thefollower 68 and the fan F will be rotated with the driver 64 and themediums will be circulated as previously described. If the poles of thefollower and driver tend to get out of step a considerable force will beproduced, by the resistance to a change in magnetism of the magnetsopposing this relative motion.

If the follower 68 is of magnetic material, such as magnetic stainlesssteel, magnetic lines of force will be set up in the follower formingmagnetic circuits, a south pole opposite the north pole of the driver 64and.a north pole opposite the south pole of the driver. When the driver64 is rotated the poles'formed in the follower 68 will tend to followthe opposing pole of the driver 64. and tend to rotate the follower dueto the resistance to a change in magnetism of the follower 6 8. If thefollower 68 tends to get out of step with the driver 62 againconsiderable force will be produced to oppose such a relative movement.

Since the fan F only needs to create a pressure difference of about 4 /2inches of water in the inert gas circuit to circulate all of the mediumswithin the appparatus, a comparatively small driving magnet can be usedand its magnetic force can be easily transmitted through the shell 69 toproduce rotation of the magnetic follower 68 and the fan F.

In Figure 3 an electric motor 9!! drives the driver mainet 64' and issupported in the casing 9| by a resiliently mounted bearing 92 and anannular rubber. ring 93 bonded to the metal rings 94 and 85 which aresecured to the motor 90 and the housing 9|, respectively. If desired,the offset portions of the rings 94 and 95 may be omitted so that therubber ring 93 will be stressed solely in shear by the weight of themotor 90 and the driver magnet 64. It is to be understood that the motor90 of Figure 3 is to be substituted for the turbine T of Figure 2 andthat the remalning parts of the apparatus will remain the same as inFigure 2. When the motor of Figure 3 is used, the steam generatingsystem of Figure 1 is omitted.

From the foregoing it will be evident that this invention has provided asimple means of posiand described but to include all eq uivalentvariations thereof except as limited by the scope of the claims.

I claim:

1. An absorption refrigerating apparatus comprising a generator, a pumpfor circulating the mediums in said apparatus, said generator comprisinga vessel divided by a partition into two chambers hermetically sealedfrom each other, one of said chambers containing a working fluid of saidapparatus and the other containing an auxiliary motive fluid, means forheating said generator to produce vapor in each of said chambers andmeans hermetically sealed from said pump and utilizing vapor from saidchamber containing the auxiliary motive fluid said pump.

.2. An absorption refrigerating apparatus comprising, a generator, arectifier, means hermetically sealed within the walls of the apparatusfor circulating the mediums therein, power means hermetically sealedfrom said circulating means for driving the same and means fortransmitting motion through the hermetically sealed walls of saidapparatus from said power means to said circulating means and means forleading liquid from said rectifier to said circulating means forlubricating the same.

3. An absorption refrigerating apparatus comprising, a generator, acondenser, an evaporator, an absorber, said condenser being positionedabove said, generator, conduits connecting said generator, evaporatorand absorber to form an inert gas circuit and a solution circuit, avertically extending conduit including a rectifier connecting saidgenerator and condenser, a gas separation chamber belowisaid rectifier,a fan hermetically sealed in said inert gas circuit for circulating gasand solution in said inert gas and solution circuits respectively, amagnetic follower directly connected to said fan, a driver magnetpositioned exteriorly of the walls of said apparatus and positioned todrive said follower through the walls of the apparatus and meansincluding a liquid trap for leading condensate from said gas separationchamber to said fan to lubricate the sme.

4. An absorption refrigerating apparatus comprising, a generator, acondenser, an evaporator, an absorber, said condenser being positionedabove said generator, conduits connecting said for driving generator,evaporator and absorber to form an inert gas circuit and a solutioncircuit, a vertically extending conduit including a rectifier connectingsaid generator and condenser, a gas separation chamber below saidrectifier, a fan hermetically sealed in said inert gas for circulatinginert gas and solution in said inert gas and solution circuitsrespectively, a magnetic follower directly connected to said fan, adriver magnet positioned exteriorly of the walls of said apparatus andpositioned to drive said follower through the walls of the apparatus,means including a liquid trap for leading condensate from said gasseparation chamber to said fan to lubricate the same, said generatorincluding a, chamber sealed from said circuit and containing anauxiliary motive fluid, means for heating said generator and meansutilizing vapor generated from said motive fluid for driving said drivermagnet.

DWIGHT L. MOODY.

REFERENCES CITED file of this patent:

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